1. Related Field
The present invention relates to a method and apparatus for additive manufacturing according to the preamble of the claims provided herein.
2. Description of Related Art
Freeform fabrication or additive manufacturing is a method for forming three-dimensional articles through successive fusion of chosen parts of powder layers applied to a worktable.
An additive manufacturing apparatus may comprise a work table on which said three-dimensional article is to be formed, a powder dispenser, arranged to lay down a thin layer of powder on the work table for the formation of a powder bed, an energy beam for delivering energy to the powder whereby fusion of the powder takes place, elements for control of the energy given off by the energy beam over said powder bed for the formation of a cross section of said three-dimensional article through fusion of parts of said powder bed, and a controlling computer, in which information is stored concerning consecutive cross sections of the three-dimensional article. A three-dimensional article is formed through consecutive fusions of consecutively formed cross sections of powder layers, successively laid down by the powder dispenser.
In additive manufacturing it is important to control the powder distribution. It is desirably to distribute a predefined amount of powder over a predetermined area. This requires a well defined method and apparatus for repeatedly removing a predetermined amount of powder from a powder storage to a powder distributor device.
One solution to the above mentioned problem of removing a predetermined amount of powder from a powder storage is disclosed in WO 2006/121374. In said document a distribution member is arranged movable a predetermined distance into a supply of powder. Said distance being sufficiently long to bring about a transfer of a predetermined portion of powder from the powder storage at one side of the distribution member to another side of the distribution member facing the working area.
A problem with said solution is that the powder quality, i.e., the powder humidity, powder composition, powder size and powder amount in the powder storage etc. may affect the amount removed from the powder storage.